FERRITE CONTENT MEASUREMENT
In stainless steel welds for example it is often required to measure the ferrite content in the weld metal. Ferrite is the body centred cubic form of iron which can form in welds due to welding methods and weld rod composition. There are usually limits set out by the codes for ferrite content in the weld material, and therefore the test is sometimes required for the weld procedure qualification record (WPQ) test.
In order to measure the ferrite content in a weld, a sample is prepared and polished for microstructural investigation. Several images are taken from the microstructure and then processed with image analysis software to determine the volume of ferrite in each of the images. This is then averaged to provide a result.
This process is similar to the wear particle analysis measurements, hence can also provide information about the size range and shape of the ferrite automatically.
This method can also be used for the measurement of inclusion contents in materials or for general phase analysis and also for porosity measurements in ceramics, or castings or sintered components.